Features of spatial distribution of oscillations in faculae regions

We found that oscillations of LOS velocity in H-alpha are different for various parts of faculae regions. Power spectra show that the contribution of low-frequency modes (1.2 - 2 mHz) increase at the network boundaries. Three and five- minute periods dominate inside cells. The spectra of photosphere and chromosphere LOS velocity oscillations differ for most faculae. On the other hand, we detected several cases where propagating oscillations in faculae were manifest with a five-minute period. Their initiation point on spatial-temporal diagrams coincided with the local maximum of the longitudinal magnetic field.Comment: 6 pages, 4 figure

Emergence of Small-Scale Magnetic Loops in the Quiet Sun Internetwork

We study the emergence of magnetic flux at very small spatial scales (less than 2 arcsec) in the quiet Sun internetwork. To this aim, a time series of spectropolarimetric maps was taken at disk center using the instrument SP/SOT on board Hinode. The LTE inversion of the full Stokes vector measured in the Fe I 6301 and 6302 A lines allows us to retrieve the magnetic flux and topology in the region of study. In the example presented here, the magnetic flux emerges within a granular structure. The horizontal magnetic field appears prior to any significant amount of vertical field. As time goes on, the traces of the horizontal field disappear while the the vertical dipoles drift -carried by the plasma motions- towards the surrounding intergranular lanes. These events take place within typical granulation timescales.Comment: 9 pages (referee format), 3 figures. Accepted for publication in ApJ Letter

Transport of magnetic flux from the canopy to the internetwork

Recent observations have revealed that 8% of linear polarization patches in the internetwork quiet Sun are fully embedded in downflows. These are not easily explained with the typical scenarios for the source of internetwork fields which rely on flux emergence from below. We explore using radiative MHD simulations a scenario where magnetic flux is transported from the magnetic canopy overlying the internetwork into the photosphere by means of downward plumes associated with convective overshoot. We find that if a canopy-like magnetic field is present in the simulation, the transport of flux from the canopy is an important process for seeding the photospheric layers of the internetwork with magnetic field. We propose that this mechanism is relevant for the Sun as well, and it could naturally explain the observed internetwork linear polarization patches entirely embedded in downflows.Comment: Accepted to Ap

Stability of graphene doping with MoO<inf>3</inf>and I<inf>2</inf>

We dope graphene by evaporation of MoO_3 or by solution-deposition of I_2 and assess the doping stability for its use as transparent electrodes. Electrical measurements show that both dopants increase the graphene sheet conductivity and find that MoO_3-doped graphene is significantly more stable during thermal cycling. Raman spectroscopy finds that neither dopant creates defects in the graphene lattice. In-situ photoemission determines the minimum necessary thickness of MoO_3 for full graphene doping.This is the author's accepted manuscript. Copyright (2014) American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Applied Physics Letters (volume 105) and may be found at http://scitation.aip.org/content/aip/journal/apl/105/10/10.1063/1.489502

Comparison of transient horizontal magnetic fields in a plage region and in the quiet Sun

Properties of transient horizontal magnetic fields (THMFs) in both plage and quiet Sun regions are obtained and compared. Spectro-polarimetric observations with the Solar Optical Telescope (SOT) on the Hinode satellite were carried out with a cadence of about 30 seconds for both plage and quiet regions located near disk center. We select THMFs that have net linear polarization (LP) higher than 0.22%, and an area larger than or equal to 3 pixels, and compare their occurrence rates and distribution of magnetic field azimuth. We obtain probability density functions (PDFs) of magnetic field strength and inclination for both regions.The occurrence rate in the plage region is the same as for the quiet Sun. The vertical magnetic flux in the plage region is ~8 times larger than in the quiet Sun. There is essentially no preferred orientation for the THMFs in either region. However, THMFs in the plage region with higher LP have a preferred direction consistent with that of the plage-region's large-scale vertical field pattern. PDFs show that there is no difference in the distribution of field strength of horizontal fields between the quiet Sun and the plage regions when we avoid the persistent large vertical flux concentrations for the plage region. The similarity of the PDFs and of the occurrence rates in plage and quiet regions suggests that a local dynamo process due to the granular motion may generate THMFs all over the sun. The preferred orientation for higher LP in the plage indicates that the THMFs are somewhat influenced by the larger-scale magnetic field pattern of the plage.Comment: 11 pages, 7 figures, A&A accepte

Recent Advances in Chromospheric and Coronal Polarization Diagnostics

I review some recent advances in methods to diagnose polarized radiation with which we may hope to explore the magnetism of the solar chromosphere and corona. These methods are based on the remarkable signatures that the radiatively induced quantum coherences produce in the emergent spectral line polarization and on the joint action of the Hanle and Zeeman effects. Some applications to spicules, prominences, active region filaments, emerging flux regions and the quiet chromosphere are discussed.Comment: Review paper to appear in "Magnetic Coupling between the Interior and the Atmosphere of the Sun", eds. S. S. Hasan and R. J. Rutten, Astrophysics and Space Science Proceedings, Springer-Verlag, 200

EUV jets, type III radio bursts and sunspot waves investigated using SDO/AIA observations

Images from the Solar Dynamics Observatory (SDO) at 211A are used to identify the solar source of the type III radio bursts seen in WIND/WAVES dynamic spectra. We analyse a 2.5 hour period during which six strong bursts are seen. The radio bursts correlate very well with the EUV jets coming from the western side of a sunspot in AR11092. The EUV jet emission also correlates well with brightening at what looks like their footpoint at the edge of the umbra. For 10-15 min after strong EUV jets are ejected, the footpoint brightens at roughly 3 min intervals. In both the EUV images and the extracted light curves, it looks as though the brightening is related to the 3-min sunspot oscillations, although the correlation coefficient is rather low. The only open field near the jets is rooted in the sunspot. We conclude that active region EUV/X-ray jets and interplanetary electron streams originate on the edge of the sunspot umbra. They form along a current sheet between the sunspot open field and closed field connecting to underlying satellite flux. Sunspot running penumbral waves cause roughly 3-min jet footpoint brightening. The relationship between the waves and jets is less clear.Comment: 4 pages, 7 figures, Accepted by A&A Letters. For associated gif movie, see http://www.mps.mpg.de/data/outgoing/innes/jets/losb_304_211_rd.gi

Detección de fenotipos de resistencia ACCSuT, BLEE y AmpC en cepas de Salmonella enterica aisladas de infecciones en animales

The aim of this study was to detect the presence of resistance profiles, ESBL (Extended Spectrum Betalactamases), AmpC (AmpC Betalactamases) and ACSSuT phenotype (resistance to oxytetracycline, ampicillin, streptomycin, sulfatrimetropim, and chloramphenicol) in Salmonella enterica isolates by using the Kirby Bauer technique. Fifty isolates of Salmonella enterica identified according to ISO standard: 6579 (2002) were taken from the Laboratory of Microbiology of the Faculty of Veterinary Medicine of the National University of San Marcos. Twenty antibiotics of relevance in human and veterinary medicine were used. The results showed that 96% (48/50) of the isolates were resistant to at least one antibiotic. The highest frequencies of resistance were presented to chloramphenicol (94%), tobramycin (72%) and oxytetracycline (49%). Low resistance was observed in aztreonam (5%), cephalosporins (2-7%), sulfatrimethoprin (4%) and gentamicin (2%), intermediate resistance to ciprofloxacin (4%) and a high sensitivity (100%) to amikacin. In addition, 2% of the isolates presented the BLEE resistance phenotype, 2% the AmpC type beta-lactamases and 2% the ACSSuT phenotype. The results highlight the importance of the information generated by the sensitivity tests and their fundamental use in the monitoring and detection of resistance patterns in Salmonella.El objetivo del estudio fue detectar la presencia de perfiles de resistencia, BLEE (Betalactamasas de Espectro Extendido), AmpC (Betalactamasas AmpC) y fenotipo ACSSuT (resistencia a oxitetraciclina, ampicilina, estreptomicina, sulfatrimetropim y cloranfenicol) en aislados de Salmonella enterica mediante el uso de la técnica de Kirby Bauer. Se utilizaron 50 aislados de Salmonella enterica identificados según norma ISO: 6579 (2002) provenientes del cepario del Laboratorio de Microbiología de la Facultad de Medicina Veterinaria de la Universidad Nacional Mayor de San Marcos. Se trabajó con 20 antibióticos de relevancia en medicina humana y veterinaria. El 96% (48/50) de los aislados fueron resistentes a por lo menos un antibiótico. Las frecuencias más altas de resistencia se presentaron al cloranfenicol (94%), tobramicina (72%) y oxitetraciclina (49%). Se observaron porcentajes de resistencia bajos en aztreonam (5%), cefalosporinas (2- 7%), sulfatrimetoprin (4%) y gentamicina (2%), resistencia intermedia a ciprofloxacino (4%) y una alta sensibilidad (100%) para amikacina. El 2% de los aislados presentó el fenotipo de resistencia BLEE, 2% el de betalactamasas tipo AmpC y 2% el fenotipo ACSSuT. Los resultados encontrados resaltan la importancia de la información generada por las pruebas de sensibilidad y su uso fundamental en la vigilancia y la detección de patrones de resistencia en Salmonella